This map was created for use by a Soviet government research institute. By means of the color coding, it shows regions in Siberia where hydrogeological investigations had been carried out and divides those regions into three categories: detailed and special hydrogeological investigations from prospectors' experience…on a scale of two versts per inch; general hydrogeological investigations…more than two versts per inch; and geological, hydrogeological, soil, and other investigations eliciting the presence of underground water. The white areas, occupying by far the largest part of the map, indicate where neither ...